White of my boston's eye turning brown...

by Jen Paige
(Sacramento, CA)

My Boston is 3 years old. There is a brown smudge like mark on the white of one of her eyes. It hasn't been there forever but seems to slowly get worse. My vet hasn't said anything about during her regular check ups. Does anyone know if this is something I should be worried about? Know what it is? It doesn't seem to bother her...